Process of dephosphorizing iron ore



UNITED STATES PATENT OEEicE.

THOMAS FRANCIS WITHERBEE,0E PORT HENRY, NEW YORK.

PROCESS OF DEPHOSPHORIZING IRON ORE.

SPECIFICATION formingpart of Letters Patent No. 400,622, dated April 2, 1889.

I Application filed December 28, 1887. $erial No. 259,237. (No specimens.)

To all whom it may concern.-

Be it known that I, THOMAS FRANCIS WITH- ERBEE, of Port Henry, in the county of Essex and State of New York, have invented a new and Improved Process of Dephosphorizing Iron Ore, of which the following is a full, clear, and exact description. 7

The object of my invention is to separate from iron ore apatite or phosphorus-bearing compounds remaining or adhering to the particles of ore after mechanical processes of separation have been applied.

In practice I find that it is easy to separate apatite and other. gangue from iron ore to a certain degree of purity by several well-known processes, notably by dry or wet magnetic separations, by washing, or by a combination of washing and'a wet or dry magnetic separation; but these processes, -however,"leave the ore witha certain percentage of phosphorus, it being impossible by the mechanical prooesses enumerated to get the phosphorus below .12 or .15 of'one per cent, and consephosphorus remaining after mechanical sep aration by above process, which eradication I bring about by submitting themechanicallypurified ore to the action of dilute acid,preferably sulphuric acid, said acid being used at the rate of fifty to one hundred pounds of acid to the ton and diluted with water, so that the solution will contain from two to five per cent. of concentrated acid. This acid solution is added to the crushed ore, .and, if necessary, heat is applied,the acid acting to dissolve the phosphorus which remains in the solution, and the sulphate of lime formed from the apatite, if the phosphorus isin that combination, will also be in the solution by reason of the Water added to the acid, as stated.

The above proportions of acid and water to the ton of ore worl; well on an ore which, as before stated, contains, after magnetic treating and washing, from .12 to .15 of one per cent. of phosphorus; but I do not confine myself to the quantities of acid specified, as they may be varied to suit the amount of phosphorus in the ore. After the phosphorus is sufficiently removed, which may be ascertained by testing the solution of the ore, the acid is drawn off from the ore, and the ore is washed with water to free it from the adhering acid, so that it may be safely handled.

By the process above described phosphorus may be sufficiently removed from low-grade ore otherwise unfit for Bessemer-steel process, so that said ore will be of high grade for such usethat is, the ore will be practically freed from phosphorus, and that, too, at such low cost as to make the process a commercial success.

Among the advantages of using sulphuric acid are its relative cheapness and the fact thatit will dissolve less of the ore than other acids, and thereby cause less waste of iron.

In carrying 'out my process it must be understood that the ore is first pulverized to such an extent as will detach the crystals of apatite from the ore. The ore is then Washed and treated magnetically, thereby mechanically removing the principal portion of the phosphate of lime, which could not be dissolved out economically by means of acid, following which the acid process is then employed, and finally all traces of acid are washed away with water. V

I wish it to be understood that the solution of acid employed shall be so weak as to have but little, if any, effect upon the ore.

IIaving thus described my invention,I claim as new and desire to secure by Letters Patent-' The process of dephosphorizing iron ore, which consists in mechanically separating apatite or phosphorus-holding compounds from iron 'ore, then dissolving the remaining small percentage ofapatite with dilute sulphuric acid, and finally Washing the ore with water, substantially as described.

. THOMAS FRANCIS WITHERBEE. Witnesses:

E. F. PAGE, J NO. G. WITHERBEE. 

